In industrial applications, one of the most important production tools is the machine tools, such as mechanical arms, wire bonding machines, computer numerical control (CNC) lathes etc. Positioning is the most important work of the machine tools, which is usually performed by the encoder. When the power is off, the machine cannot interpret the location changing information. When the power is restored, the machine tools performs home-return calibration using the encoder to retrieve the origin of the location.
Conventional encoders usually use a backup battery. When the power system supplies power normally, the encoder is powered by the power system. When power is off, the encoder is powered by the backup battery. However, it increases production costs because that backup batteries need to be replaced regularly.